This invention relates to harvesters, but more particularly, the invention relates to an endless member adapted for cutting, gathering, conveying, or the like.
In harvesting equipment, it is sometimes advantageous to use power transmission belts for performing work in addition to their normal function of power transmission. One or more working elements, such as a crop cutter or crop gatherer, may be attached to the exterior of the belt, Examples of such devices appear in U.S. Pat. Nos. 2,728,181; 2,782,582; 2,867,069; 3,397,524; 3,545,188; 3,651,626; and 3,699,757. While such belts offer many advantages in the sphere of crop harvesting, they are not free of problems. Belts with cutters are driven at approximately 8,000 to 12,000 feet per minute to effect impact cutting while belts with crop engaging fingers are driven up to a few hundred feet per minute to effect crop conveying.
Long belt spans are required for agricultural type cutters or mowers. The long spans and attached cutters may cause the belt to longitudinally or torsionally vibrate at such a frequency as to cause instability which may result in the belt disengaging from its sheaves. Heretofore and as disclosed in U.S. Pat. No. 3,651,626, instability caused by a twisting force on the cutter may be reduced by locating the center of gravity of the cutter element over the belt center with connectors extending through or from the belt center at alignment accuracy of one degree or less. The Patent also teaches that the belt jacket may be two plies of nylon or dacron, and the belt body may be fiber load to produce " . . . maximum torsional modulus" which, in turn, improves stability.
While the prior art may offer some partial solutions to the problem of belt stability, they do not offer total solutions, but rather introduce some design limitations. For example, the cutter is purposely not offset from the edge of the belt to space the plane of the sheaves away from the foliage being cut. Such a displacement, the art teaches, offsets the center of gravity of the cutter causing belt twisting. Also, the art indicates that maximum torsional modulus may only be achieved with a multiple ply belt jacket and fiber loading of the stock which may inhibit longitudinal flexibility for bending around sheaves, or impose economic burdens associated with construction thereof.